title: Overdrive versus conventional or closed-loop rate modulation pacing in the prevention of atrial tachyarrhythmias in Brady-Tachy syndrome: on behalf of the Burden II Study Group.
abstract: BACKGROUND
  Optimizing dual-chamber pacing to prevent recurrences of atrial tachyarrhythmias (AT) in sinus node dysfunction is still debated. Despite the large number of studies, efficacy of sophisticated preventive algorithms has never been proven. It is not clear whether this is due to imperfect study designs or to a substantial inefficacy of pacing therapies.
  
  
  OBJECTIVE
  To intraindividually compare AT burden between an atrial overdrive and two heart rate modulation approaches: a conventional accelerometric-sensor-based DDDR mode and a contractility-driven rate responsive closed loop (CLS) algorithm.
  
  
  RESULTS
  Four hundred fifty-one patients with Brady-Tachy syndrome (BTS), severe bradycardia, and a documented episode of atrial fibrillation were enrolled. One month after implant, each pacing therapy was activated for 3 months in random order. A simple log transformation was used to handle large and skew AT burden distributions. Estimates were adjusted for false-positive AT episodes and reported as geometric means (95% confidence interval). A significantly higher AT burden was observed during overdrive, 0.14% (0.09%, 0.23%) (adjusted, 0.12%[0.07%, 0.20%]). Both DDDR and CLS performed better: respectively, 0.11% (0.07%, 0.17%) (adjusted, 0.08%[0.05%, 0.14%]), 0.06% (0.03%, 0.09%) (adjusted, 0.04%[0.03%, 0.07%]). All the comparisons were statistically significant. During overdrive significantly more patients had AT episodes of duration between 1 minute and 1 hour. No significant differences were observed for longer episodes.
  
  
  CONCLUSIONS
  Atrial overdrive showed the worst performance in terms of AT burden reduction and should not be preferred to heart rate modulation approaches that still have to be considered as a first-choice pacing mode in BTS.
authors.affiliation: Department of Cardiology, S Giovanni Calibita Fatebenefratelli Hospital, Rome, Italy. andrea.puglisi.ag@alice.it
authors.forename: Andrea
authors.initials: A
authors.lastname: Puglisi
authors.forename: Stefano
authors.initials: S
authors.lastname: Favale
authors.forename: Pietro
authors.initials: P
authors.lastname: Scipione
authors.forename: Donato
authors.initials: D
authors.lastname: Melissano
authors.forename: Letterio
authors.initials: L
authors.lastname: Pavia
authors.forename: Francesco
authors.initials: F
authors.lastname: Ascani
authors.forename: Massimo
authors.initials: M
authors.lastname: Elia
authors.forename: Alberto
authors.initials: A
authors.lastname: Scaccia
authors.forename: Antonio
authors.initials: A
authors.lastname: Sagone
authors.forename: Bruno
authors.initials: B
authors.lastname: Castaldi
authors.forename: Emilio
authors.initials: E
authors.lastname: Musacchio
authors.forename: Giovanni Luca
authors.initials: GL
authors.lastname: Botto
mesh_terms: D000368:Aged; D001919:Bradycardia / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000379:methods* / Q000706:statistics & numerical data*; D015897:Comorbidity; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013612:Tachycardia, Ectopic Atrial / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D016896:Treatment Outcome